For shopping - try Chapel Street, Swanston and Bourke Street.
Victoria Market for cheap stuff. Try their jam doughnuts
I think they are not open on Tues. Cannot remember day
For sights - the must go are Great Ocean Road, The Pinnacles and Phillip Island
There are others like Ballarat and Werribee open zoo.
Things to do - If you are going during the June sch holidays, go skiing. I went to Mt Buller
There is another MT, i think its MT Horsham. Not sure again. MT Buller is slightly more expensive.
Crown Casino to gamble. Remember to bring your IC
Makan joints - La Pochetta, opp Victoria MArket. Great pizza and pasta at rock bottom prices. 1 large pizza for about $9 bucks. 1999 prices.
Lygon street for fine dinning
Thats all for now
For Sydney, only know the Opera house. Did not study there so not sure. Was only there for 5 days. Can visit The Rocks as well. Its an open air market